Problem Solved! I followed the instructions on how to uninstall Photos as described at
  1. Run Windows Powershell as Admin
  2. Copy and paste the following into the Powershell command line: Get-AppxPackage *photos* | Remove-AppxPackage
  3. Close Powershell
  4. Upon next inserting of media, Windows will ask what program to open... select the program of your choice.

Thanks to all who tried to solve this problem.